Grinding machine having rotatable wheel dressing tool



Nov. 18, 1958 G. A. HIDER 2 GRINDING MACHINE HAVING ROTATABLE WHEELDRESSING TOOL Filed Sept. 21, 1956 2 Sheets-Sheet 1 INVENTOR.

GLENN A. H] DER Qua/Z25 ATTORNEY Nov. 18, 1958 G. A. HIDER GRINDINGMACHINE HAVING ROTATABLE WHEEL DRESSING TOOL Filed Sept. 21, 1956 2Sheets-Sheet 2 in I 56 I F|G 5 IT! 29 l 28 United States Patent GRINDINGMACHINE HAVING ROTATABLE WHEEL DRESSING TOOL Glenn A. Hider, Penfield,N. Y., assignor to The Gleason Works, Rochester, N. Y., a corporation ofNew York Application September 21, 1956, Serial No. 611,227 8 Claims.(Cl. 125-11) The present invention relates to grinding machines and isespecially concerned with the mounting means for the tools employed onsuch machines for dressing the grinding wheels thereof.

Diamond-tipped tools are frequently used for this purpose, and it isknown practice to periodically rotate such a 'tool through a small angleto thereby present a new face of the diamond to the grinding wheel. Inthis way wear is distributed around the diamond causing the life of thetool to be prolonged, and the facets worn on the diamond are preventedfrom becoming so enlarged as to impair wheel-dressing efficiency.

,An object of the present invention is a rugged mechanism forperiodically turning the tool by uniform increments. Such mechanismincludes an actuator which will upon each operation thereof advance arotatable member through a simple fraction of a revolution, and aconnection between the-rotatable member and the tool arranged to advancethe tool through a different angle than the member. This difference ofangle is such that the tool repeats its position only after it has madea number of complete revolutions; and because of this, after eachadvance, the edge of a facet of the tool, rather than a flat surfacethereof, is presented to the wheel. As a result, a more efficientwheel-dressing action is obtained and the formation of wide facets onthe tool, which lead to ineflicient dressing action, is prevented.

In certain conventional machines the dressing tool is periodicallyadvanced into the path of the rotating abra-- sive wheel, and either thetool or the wheel is then moved to cause the tool to traverse andthereby dress the active surface of the wheel, after which the tool isretracted from the path of the wheel. The present invention provides forthe tool to be rotatively advanced once for each cycle of its advanceand retraction with respect to the path of the wheel, so that for eachdressing operation a fresh edge of the tool is presented to the wheel.

The foregoing and other objects and advantages will appear from thefollowing description made with reference to the accompanying drawingsillustrating an application of the invention to a cutter sharpeningmachine. In the drawings:

Fig. 1 is a front view, partly in vertical section, of the parts of themachine related to the invention;

Fig. 2 is a detail sectional view in plane 2-2 of Fig.

Fig. 3 is a diagram of the hydraulic system for moving the dresser tool;

Fig. 4 is a vertical sectional view through the dressing tool and itssupporting head, in the broken plane indicated by line 4 4 of Fig. 5;and,

Fig. 5 is a sectional view in plane 55 of Fig. 4.

The machine illustrated fragmentarily in Fig. 1 may be of the generaltype disclosed in Patent No. 2,224,959 to C. T. Galloway, and comprisesa frame on which is supported a wheel head 11. In this head is journaleda spindle 12 supporting a grinding wheel 13 for rotation about axis 14.The head is swingable on a horizontal slide, not shown, about a verticalaxis 15, to thereby pass the active conical surface 16 of wheel 13 backand forth over a workpiece, which also is not shown and which in thiscase is a cutter to be sharpened. The head and its supporting horizontalslide are periodically moved back and forth in the direction of arrow 17to cause the dressing tool to traverse the surface 16.

This tool comprises a diamond tipped element 18 and a holder 19, theelement being secured in coaxial position in the holder by a set screw21. Upon loosening of the set screw the element 18 may be adjusted alongits axis, 22, by turning a screw 23 which is threaded into the holderand has a conical tip engaging the element 18. The tool 18, 19 issupported on a pair of spaced coaxial ball-type anti-friction bearings24 for rotation about axis 22. The inner races of these bearings fit thecylindrical shank of holder 19 and are spaced by a sleeve 25, while theouter races fit into a flanged tubular part 26 and are spaced by asleeve 27. Tubular part 26 constitutes a part of tool head 28, itsflange being secured to the head proper by screws, not shown. As shownin Fig. 1 the axis 22 is slightly inclined to a perpendicular from theadjacent active surface 16 of the wheel.

For the purpose of effecting a step-by-step rotation of tool 18, 19, apiston 29 is arranged to reciprocate in a cylinder bore 32 in the toolhead provided with sealing rings 31 and which is pivoted to it by a pin33. The pawl is held engaged with a sleeve-shaped ratchet wheel 35 by aplunger 36 backed by a spring 37 and retainer plug 38. As shown, thepawl is disposed in a slot 39 in the piston H 29, and a key 41 projectsinto this same slot to prevent the piston from turning in the cylinderbore 32. Retro' gression of the ratchet wheel, i. e. clockwise motion inFig. 5, is prevented by a holding pawl 42 which is slidable in the toolhead and is backed by a spring 43 which is retained by a cap 44. Thiscap, which also retains the piston 29, is secured to the tool head 28 byscrews 45, one of which is shown in Fig. 5. A flexible ring 46 providesa hydraulic seal between the parts 44 and 28.

The ratchet wheel 35 is rotatable about axis 22 on the outside of theshank of a sleeve-like gear 47 which is keyed at 48 to the lower end oftool holder 19. The gear 47, the ratchet wheel and the tool holder 19,are held in assembly by a washer 49 and a screw 51. Formed integrallywith the ratchet wheel is a gear 52 which is of substantially the samediameter as the gear 47. Both gears 47 and 52 mesh with an elongatedpinion 53, this pinion being rotatable on a shaft 54 that is held in thetool head by a press-fitted washer 55.

Upon each forward stroke of the piston, to the left in Fig. 3 andupwardly in Fig. 5, the ratchet wheel is' of teeth (twenty-two)throughout its length, the tool 18,

19 is turned through slightly more than nine degrees during each forwardstroke of the piston, and for each complete turn of the ratchet wheel isturned through slightly more than one turn (42/41 revolutions). Moreoverforty-one complete turns of the ratchet wheel are required to cause thetool to exactly repeat its position in the tool head. As a result ofthis, after each ratchet operation there is presented to the grindingwheel an edge of the tool tip instead of a plane facet that has beenworn on the tip during a preceding dressing operation.

The dresser head 28 is secured to the rod 56 of a piston 57 which isreciprocable vertically within a cylinder 58 secured to the machineframe 10. A key 59 engages in a keyway in the piston rod to hold thehead Patented Nov. 18, 1958 28. The piston is carries a pawl 34 andpiston assembly against rotation. As shown in Fig. 3, the upper andlower chambers of cylinder 58 are connected respectively by hydrauliclines 61 and 62 to a reversing valve 63, and, by branch lines 64 and65,- to the opposite fluid chambers of cylinder bore 32. The reversingvalve is also connected to a hydraulic pressure line '66 and a returnline 67 extending to a suitable pump or other source of hydraulicpressure, not shown. Prior to each wheel dressing the valve is operatedto connect pressure line 66 to' lines 62 and 65, and return line 67 tolines 61 and 64. Accordingly the piston 57 is raised to its upper limitposition shown in Figs. 1 and 3, wherein the tip of tool 18 lies in thepath of surface 16 of the abrasive wheel. Simultaneously the piston 29is moved through its return or ratchet-reset stroke, i. e. to the rightin Fig. 3 and downwardly in Fig.- 5. During this stroke the pawl 42holds the ratchet wheel against motion, and the pawl 34 rides idly overthe adjacent teeth of the ratchet wheel. The actual dressing operationis then effected by movement of the abrasive wheel to the right in Fig.1, to draw the wheel surface 16 across the tip of tool 18. At theconclusion of this operation the valve 63 is reversed to connectpressure line 66 to lines 61 and 64, and lines 62 and 65 to return line67. This causes the piston to lower, retracting the dressing tool fromthe path of the abrasive wheel, and simultaneously moves piston 29 tothe left in Fig. 3, upwardly in Fig. 5, to advance the tool rotativelyin the tool head in preparation for the next dressing operation. Thisrotational advance of the tool during its retraction by the piston 57assures that such advance will be completed prior to the actual dressingoperation. Having now described and explained the operation of theinvention, what is claimed is:

e 1. A machine comprising a tool head, a wheel dressing tool rotatablein the head, actuating means including a member rotatable step-by-stepin the head about the same axis as the tool, a drive gear co rotatablewith said member, a driven gear co-rotatable with the tool, and a pinionmeshing with both gears.

2. A machine according to claim 1 in which the tooth number ratio of thedrive gear to the pinion is diiferent from that of the driven gear tothe pinion.

3. A machine according to claim 2 in which said member is a ratchetWheel and said actuating means further comprises a member reciprocablein the head and a pawl carried thereby and engageable with the ratchetWheel for effecting the step-by-step rotation thereof.

4. A machine comprising a tool head, a wheel dressing tool rotatable inthe head, actuating means including a ratchet wheel rotatablestep-by-s'tep in the head, and drive gearing connecting the ratchetwheel and the tool, said gearing being of such ratio that the angle ofadvance of the tool differs from that of the ratchet wheel and that thetool repeats its position only after making a plurality of turns.

5. A grinding machine having an abrasive wheel and a dressing tool forthe wheel, a tool head in which the tool is mounted for rotation, thetool head and the abrasive wheel being mounted on the machine forrelative motion to bring the tool and the Wheel into and ing connectingthe ratchet wheel and the tool of such drive ratio that the angle ofadvance of the tool dilfers from that of the ratchet wheel, said gearingincluding a drive gear co-rotatable with the ratchet wheel, a driven.

gear co-rotatable with the tool, and a pinion meshing with both gears.

6. A grinding machine having an abrasive wheel and a dressing tool forthe wheel, a tool head in which the tool is mounted for rotation,actuating means including a member rotatable step-by-step in said headthrough increments each of which is a simple fraction of one completerevolution, and gearing connecting said member to the tool which gearingis of such drive ratio that the angle of each rotative advance of thetool differs from that of said member, said gearing comprising a drivegear co-rotatable with said member, a driven member co-rotatable withthe tool, and a pinion meshing with both gears.

'7. A machine comprising a tool head, a wheel dressing tool, axiallyspaced anti-friction bearings supporting the tool for rotation in thetool head, a fiuid actuated piston reciprocable in said head, a ratchetwheel rotatable in the head in coaxial relation to said bearings, a pawlactuated by the piston and engageable with the wheel for effectingstep-by-step rotation thereof upon reciprocation of the piston, anotherpawl engageable with the ratchet wheel for preventing retrogression ofthe latter, a drive gear co-rotatable with the ratchet wheel, a drivengear co-rotatable with the tool, and a pinion meshing with both gears,the tooth number ratio of the drive gear to the pinion being differentfrom that of the driven gear to the pinion.

8. A machine comprising a tool head, a wheel dressing tool, axiallyspaced anti-friction bearings supporting the tool for rotation in thetool head, a member reciprocable in said head, a ratchet wheel rotatablein the head in coaxial relation to said bearings, a pawl actuated bysaid member and engageable with the wheel for effecting step-by-steprotation thereof upon reciprocation of the member, another pawlengageable with the ratchet wheel for preventing retrogression of thelatter, a drive gear co-rotatable with the ratchet wheel, a driven gearco-rotatable with the tool, and a pinion meshing with both gears, thetooth number ratio of the drive gear to the pinion being different fromthat of the driven gear to the pinion.

References Cited in the file of this patent UNITED STATES PATENTS1,997,551 Romaine Apr. 9, 1935 2,628,608 Loecy Feb. 17, 1953 2,648,171Hill Aug. 11, 1953 2,741,240 Kartscher Apr. 10, 1956

